U.S. patent number 11,119,518 [Application Number 16/651,834] was granted by the patent office on 2021-09-14 for voltage regulation circuit.
This patent grant is currently assigned to ECONOPOWER PTY LTD. The grantee listed for this patent is Econopower Pty Ltd. Invention is credited to Mark Barber, Shaune Speed.
United States Patent |
11,119,518 |
Speed , et al. |
September 14, 2021 |
Voltage regulation circuit
Abstract
The present disclosure relates to a voltage regulation circuit
(100). The voltage regulation circuit (100) comprises a transformer
(130) having a primary winding (132) having a first end (132A) and
a second end (132B), and a first secondary winding (134) having a
first end (134A) and a second end (134B), wherein the first end
(132A) of the primary winding (132) is configured to receive an
input voltage and the second end (132B) of the primary winding
(132) is configured to produce an output voltage, wherein the first
end (134A) of the first secondary winding (134) is connected to a
neutral node (180), wherein the primary winding (132) produces a
primary voltage based on the input voltage, and wherein a secondary
voltage of the first secondary winding (134) is out-of-phase to the
primary voltage of the primary winding (132); and a first switch
(160) configured to connect the second end (134B) of the first
secondary winding (134) with the second end (132B) of the primary
winding (132), wherein, when the first switch (160) is connected,
the output voltage is the secondary voltage.
Inventors: |
Speed; Shaune (MacMasters
Beach, AU), Barber; Mark (MacMasters Beach,
AU) |
Applicant: |
Name |
City |
State |
Country |
Type |
Econopower Pty Ltd |
MacMasters Beach |
N/A |
AU |
|
|
Assignee: |
ECONOPOWER PTY LTD (Macmasters
Beach, AU)
|
Family
ID: |
1000005802942 |
Appl.
No.: |
16/651,834 |
Filed: |
August 31, 2018 |
PCT
Filed: |
August 31, 2018 |
PCT No.: |
PCT/AU2018/000157 |
371(c)(1),(2),(4) Date: |
March 27, 2020 |
PCT
Pub. No.: |
WO2019/060941 |
PCT
Pub. Date: |
April 04, 2019 |
Prior Publication Data
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|
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Document
Identifier |
Publication Date |
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US 20200249708 A1 |
Aug 6, 2020 |
|
Foreign Application Priority Data
|
|
|
|
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Sep 29, 2017 [AU] |
|
|
2017903958 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H02M
5/12 (20130101); G05F 1/14 (20130101) |
Current International
Class: |
G05F
1/10 (20060101); G05F 1/14 (20060101); H02M
5/12 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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|
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2438880 |
|
Dec 2007 |
|
GB |
|
940147 |
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Jun 1982 |
|
SU |
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Other References
International Search Report for PCT/AU2018/000157, dated Nov. 8,
2018, 3 pages, Australia. cited by applicant .
Written Opinion for PCT/AU2018/000157, dated Nov. 8, 2018, 4 pages,
Australia. cited by applicant.
|
Primary Examiner: Berhane; Adolf D
Attorney, Agent or Firm: Stinson LLP
Claims
The invention claimed is:
1. A voltage regulation circuit comprising: a transformer having a
primary winding having a first end and a second end, and a first
secondary winding having a first end and a second end, wherein the
first end of the primary winding and a neutral node configured to
receive an input voltage and the second end of the primary winding
and the neutral node configured to produce an output voltage,
wherein the first end of the first secondary winding is connected
to the neutral node, wherein the primary winding produces a primary
voltage based on the input voltage, and wherein a secondary voltage
of the first secondary winding is out-of-phase to the primary
voltage of the primary winding; and a first switch configured to
connect the second end of the first secondary winding with the
second end of the primary winding, wherein, when the first switch
is connected, the output voltage is the secondary voltage.
2. The voltage regulation circuit of claim 1, wherein the
transformer further comprising: a second secondary winding having a
first end and a second end, wherein the first end of the second
secondary winding is connected to the neutral node; and wherein the
voltage regulation circuit further comprises a second switch
configured to connect the second end of the second secondary
winding to the neutral node, wherein, when the second switch is
connected and the first switch is disconnected, the output voltage
is substantially the input voltage, and wherein, when the second
switch is disconnected and the first switch is connected, the
output voltage is the secondary voltage.
3. The voltage regulation circuit of claim 1, further comprising:
an input filter configured to receive the input voltage, to filter
the input voltage, and to provide the filtered input voltage to the
first end of the primary winding.
4. The voltage regulation circuit of claim 3, wherein the input
filter is a low pass filter.
5. The voltage regulation circuit of claim 1, further comprising:
an output filter configured to receive the output voltage, to
filter the output voltage, and to provide the filtered output
voltage.
6. The voltage regulation circuit of claim 5, wherein the output
filter is a low pass filter.
7. The voltage regulation circuit of claim 2, further comprising: a
processor or a Complex Programmable Logic Device configured to
provide a first control signal to control the first switch and a
second control signal to control the second switch.
8. The voltage regulation circuit of claim 7, wherein the first
control signal and the second control signal are pulse width
modulation signals.
9. The voltage regulation circuit of claim 8, wherein the first
control signal comprises first pulses, wherein the start of each of
the first pulses comprises second pulses configured to reduce
voltage spikes in the voltage regulation circuit.
10. The voltage regulation circuit of claim 9, wherein the second
pulses are dependent on a load of the voltage regulation
circuit.
11. The voltage regulation circuit of claim 8, wherein the width of
each of the first pulses of the first control signal controls a
power factor of the output voltage.
12. The voltage regulation circuit of claim 2, further comprising:
an input filter configured to receive the input voltage, to filter
the input voltage, and to provide the filtered input voltage to the
first end of the primary winding.
13. The voltage regulation circuit of claim 12, wherein the input
filter is a low pass filter.
14. The voltage regulation circuit of claim 12, further comprising:
an output filter configured to receive the output voltage, to
filter the output voltage, and to provide the filtered output
voltage.
15. The voltage regulation circuit of claim 14, wherein the output
filter is a low pass filter.
Description
STATEMENT OF RELATED CASES
This application is a national application filed under 35 U.S.C.
.sctn. 371 of International Application No. PCT/AU2018/000157,
filed Aug. 31, 2018, which claimed priority to Australian Patent
Application No. 2017903958, filed Sep. 29, 2017, the entire
contents of both of which are incorporated herein by reference in
their entireties.
TECHNICAL FIELD
The present invention relates generally to voltage regulation and,
in particular, to voltage regulation of mains electricity using a
non isolated transformer circuit.
BACKGROUND
Mains electricity delivered to homes and offices is typically
higher then specified. For example, in Australia, the mains
electricity is specified as having a voltage of 220 Vac, but
typically the mains electricity is delivered at a voltage of 255
Vac. The higher voltage leads to a higher current at an appliance
(i.e., a load), which ultimately results in a higher power being
dissipated by the appliance.
There are two major impacts resulting from the higher voltage.
First, the higher voltage and current put electrical stress on
appliances and reduces the lifespan of the appliances. Second, the
increased power equates to an increase in power consumption and
costs.
Conventional voltage reduction methods involve significant
modification to the input voltage and often lead to significant
energy losses. Therefore, such conventional methods are not
suitable in reducing the voltage of mains electricity.
Therefore, there is a need to provide a voltage reduction technique
that is highly efficiency (i.e., minimal loss of energy during
regulation).
SUMMARY
Disclosed are arrangements which seek to provide a voltage
reduction with high efficiency (i.e., minimal energy loss).
An aspect of the present disclosure provides a voltage regulation
circuit that is capable of reducing the voltage of mains
electricity by a certain voltage (e.g., 30 Vac) using a
non-isolated series transformer.
According to a first aspect of the present disclosure, there is
provided a voltage regulation circuit comprising: a transformer
having a primary winding having a first end and a second end, and a
first secondary winding having a first end and a second end,
wherein the first end of the primary winding is configured to
receive an input voltage and the second end of the primary winding
is configured to produce an output voltage, wherein the first end
of the first secondary winding is connected to a neutral node,
wherein the primary winding produces a primary voltage based on the
input voltage, and wherein a secondary voltage of the first
secondary winding is out-of-phase to the primary voltage of the
primary winding; a first switch configured to connect the second
end of the first secondary winding with the second end of the
primary winding, wherein, when the first switch is connected, the
output voltage is the secondary voltage.
Other aspects are also disclosed.
BRIEF DESCRIPTION OF THE DRAWINGS
At least one embodiment of the present invention will now be
described with reference to the drawings, in which:
FIG. 1 shows a voltage regulation transformer circuit in accordance
with an aspect of the present disclosure;
FIGS. 2A and 2B show an example of an output voltage waveform of
the voltage regulation transformer circuit of FIG. 1;
FIG. 3 shows control signals that are applied to the voltage
regulation transformer circuit of FIG. 1 to generate the output
voltage waveform shown in FIGS. 2A and 2B; and
FIGS. 4A to 4C show equivalent circuits of certain parts of the
voltage regulation transformer circuit of FIG. 1.
DETAILED DESCRIPTION INCLUDING BEST MODE
Where reference is made in any one or more of the accompanying
drawings to steps and/or features, which have the same reference
numerals, those steps and/or features have for the purposes of this
description the same function(s) or operation(s), unless the
contrary intention appears.
FIG. 1 shows a voltage regulation transformer circuit 100 having an
input filter 120, an output filter 140, a series transformer 130, a
first switch 160, and a second switch 170. An input voltage of the
voltage regulation transformer circuit 100 is applied to an input
node 110 and a neutral node 180. An output voltage of the voltage
regulation transformer circuit 100 is provided between an output
node 150 and the neutral node 180.
The series transformer 130 includes a primary winding 132, a first
secondary winding 134, and a second secondary winding 136. As
indicated by the dots, the winding polarities of the primary
winding 132 and the first secondary winding 134 are 180.degree.
out-of-phase. Also indicated by the dots, the winding polarities of
the primary winding 132 and the second secondary winding 136 are
in-phase (i.e., a phase shift of 0.degree.).
The secondary voltage at the first secondary winding 134 (which is
induced by the primary voltage of the primary winding 132) depends
on the ratio of the windings between the primary winding 132 and
the first secondary winding 134. The ratio between the primary
winding 132 and the first secondary winding 134 can be adjusted by
varying the number of turns in the first secondary winding 134. The
number of turns in the first secondary winding 134 can be varied
using a tap (not illustrated).
Other components such as switch protection devices, diode bridges,
and the like have been omitted for clarity purposes.
The input node 110 is connected to the filter 120. The filter 120
is a low pass filter to remove high frequency components of the
input voltage that might affect the voltage regulation transformer
circuit 100. The cutoff frequency of the low pass filter 120 can be
set at a value to ensure that noise at the input node 110 has
minimal effects to the circuit 100. The input filter 120 has a
switch capacitance to allow its characteristics to be changed as
required during active regulation. In one arrangement, the input is
the mains electricity. The filter 120 in turn is connected to a
first end (marked by the dot) 132A of the primary winding 132. A
second end 132B of the primary winding 132 is connected to the
output filter 140, which in turn is connected to the output node
150. The output filter 140 is a low pass filter to smooth the
output voltage and remove unwanted high frequency components
resulting from the voltage regulation transformer circuit 100. The
cutoff frequency of the low pass filter 140 can be set at above
50/60 Hz to remove the effects of the control signals 310 and 320
(described hereinafter in relation to FIG. 3). A first end (marked
by the dot) 134A of the first secondary winding 134 is connected to
the neutral node 180. A second end 134B of the first secondary
winding 134 is connected to the switch 160. The switch 160 is in
turn connected to the second end 132B of the primary winding
132.
When the switch 160 is closed (i.e., connected), the second end
134B of the first secondary winding 134 is connected to the second
end 132B of the primary winding 132. The switch 170 must be open
(i.e., disconnected) at this stage. If the switch 170 is closed at
the same time as the switch 160 is closed, there is effectively a
short circuit across the primary winding 132 and the first
secondary winding 134. In other words, when the switches 160 and
170 are closed at the same time, there is a short circuit across
the input node 110 and the neutral node 180.
FIG. 4A shows an equivalent circuit of the connection between the
primary winding 132 and the first secondary winding 134 when the
switch 160 is closed and the switch 170 is open. As seen in FIG.
4A, when the switch 160 is closed and the switch 170 is open, then
the voltage at the second end 132B is the secondary voltage of the
first secondary winding 134 and the output voltage at the output
node 150 is the secondary voltage of the first secondary winding
134 that is filtered by the output filter 140.
When the switch 160 is closed and the switch 170 is open, current
flows in the primary winding 132 generating a first flux in the
core of the transformer 130. The first flux then induces current to
flow in the first secondary winding 134, which generates a second
flux that is opposite to the first flux. As the first flux and the
second flux are opposite, the net result in a reduction in the flux
in the core of the transformer 130, which means that the primary
voltage across the primary winding 132 is reduced.
When the switch 160 is open (i.e., disconnected), the second end
134B of the first secondary winding 134 is disconnected from the
second end 132B of the primary winding 132. The switch 170 can be
either closed or open at this stage. This configuration results in
an open circuit for the first secondary winding 134, which means
the secondary voltage across the first secondary winding 134 is not
generated.
FIG. 4B shows an equivalent circuit of the connection between the
primary winding 132 and the first secondary winding 134 when the
switches 160 and 170 are open. As seen in FIG. 4B, when the switch
160 is open, then the output voltage at the output node 150 is
effectively the input voltage reduced by voltage drops across the
input filter 120, the primary winding 132, and the output filter
140. The situation where both 160 and 170 are open is not ideal and
only happens during transition of the alternate closing of the
switches 160 and 170.
The connection between the primary winding 132 and the second
secondary winding 136 is now described. A first end (marked by the
dot) 136A of the second secondary winding 136 is connected to the
neutral node 180. A second end 136B of the second secondary winding
136 is connected to the switch 170. The switch 170 is in turn
connected to the neutral node 180.
When the switch 170 is closed (i.e., connected) while the switch
160 is open, the second end 136B of the second secondary winding
136 is connected to the neutral node 180. This configuration
results in a short circuit in the second secondary winding 136. The
impedance in the short-circuited second secondary winding 136 is
then reflected to the primary winding 132. This results in the
primary winding having a nominal impedance of zero due to the
reflected impedance from the short-circuited second secondary
winding 136. The voltage at the second end 132 is effectively the
input voltage, while the output voltage at the output node 150 is
then effectively the input voltage at the input node 110 that is
filtered by the output filter 140. When the switch 170 is closed,
the switch 160 must be open to prevent creating a short circuit
across the primary winding 132 and the first secondary winding 134
as described hereinbefore.
FIG. 4C shows an equivalent circuit of the connection between the
primary winding 132 and the second secondary winding 136 when the
switch 170 is closed and the switch 160 is open. As seen in FIG.
4C, the output voltage is effectively the input voltage at the
input node 110.
Table 1 below shows the relationships between the input voltage
applied at the input node 110, the output voltage at the output
node 150, and the state of the switches 160 and 170:
TABLE-US-00001 TABLE 1 Input Secondary Output Voltage at Voltage at
the Voltage at Switch Switch the input first secondary the output
160 170 node 110 winding 134 node 150 Closed Open Vin Vs Vs
(220--see FIG. 2B) Open Closed Vin 0 Vin (effectively 210--see FIG.
2B) Open Open Vin 0 Vin (effectively 210--see FIG. 2B) Closed
Closed Vin Vs NA
In one example, an input voltage of 250 Vac is applied at the input
node 110 and the neutral node 180. The ratio of the windings
between the primary winding 132 and the first secondary winding 134
is calculated to deliver the required voltage drop, and then the
out-of-phase secondary voltage of the first secondary winding 134
induced by the primary winding 132 is a ratio of the turns, of the
primary voltage. As an example, if the ratio of the windings
between the primary winding 132 and the first secondary winding 134
is 10 to 9, then the out-of-phase secondary voltage of the first
secondary winding 134 induced by the primary winding 132 is
9/10.sup.th of the primary voltage. Therefore, the out-of-phase
secondary voltage of the first secondary winding 134 in this
example is 225 Vac.
When the switch 160 is closed and the switch 170 is open, the
voltage at the second end 132B is 225 Vac (i.e., the secondary
voltage of the first secondary winding 134. When the switch 160 is
open and the switch 170 is closed, the voltage at the second end
1328 is 250 Vac (assuming the voltage drops across the filter 120
and the primary winding 132 are negligible). When the switch 160 is
open and the switch 170 is open, the voltage at the second end 132B
is 250 Vac (assuming the voltage drops across the filter 120 and
the primary winding 132 are negligible). As described hereinafter,
the switches 160 and 170 are alternately closed, thereby changing
the voltage at the second end 132B. In this example, the voltage at
the second end 132B alternates between 225 Vac (when the switch 160
is closed and the switch 170 is open) and 250 Vac (when the switch
160 is open and the switch 170 is closed). The output voltage at
the node 150 is therefore the average voltage at the second end
132, where the average voltage depends on the duration of the
respective voltages of 225 Vac and 250 Vac at the second end 132B
and the output filter 140.
As described hereinbefore, the switches 160 and 170 are never
closed at the same time.
FIG. 2A shows the output voltage waveform at the second end 132B
when the switches 160 and 170 are being switched in an closed/open
sequence (which are associated with the control signals shown in
FIG. 3). FIG. 2B shows an enlarged view of the voltage waveform
shown in FIG. 2A. The voltage at the level indicated by the
reference numeral 210 is effectively the input voltage at the input
node 110. When the switch 160 is closed, the voltage drops to the
level indicated by the reference numeral 220.
FIG. 3 shows two control signals 310 and 320 where a first control
signal 310 controls the switching of the switch 160 and a second
control signal 320 controls the switching of the switch 170. When
the first control signal 310 is high, then the switch 160 is
closed. The switch 160 is open when the first control signal 310 is
low. When the second control signal 320 is high, then the switch
170 is closed. The switch 170 is open when the second control
signal 320 is low.
The first and second control signals 310 and 320 are pulse width
modulated signals. A pulse width 312 of the first control signal
310 corresponds to the duration that the switch 160 is closed.
Therefore, the voltage drop at the second end 132B is regulated by
the pulse width 312 of the first control signal 310.
The closing of the switch 160 by the first control signal 310 may
cause inrush currents and voltage spikes. To minimise such inrush
currents and voltage spikes, the first control signal 310 is pulsed
at the beginning of the pulse width 312, as shown by the pulses
314, before the first control signal 310 is held at the high
level.
The pulses 314 of the first control signal 310 are load adaptive,
as the number of pulses 314, the width of each pulse 314, and the
frequency of the pulses 314 are varied dependent on the load of the
voltage regulation circuit 100. The number of pulses 314, the width
of each pulse 314, and the frequency of the pulses 314 also
determine the power efficiency of the voltage regulation circuit
100. The number of pulses 314 is increased when the output voltage
of the circuit 100 is being used by higher loads.
The power factor of the voltage regulation circuit 100 can also be
varied by varying the pulse width 312. The pulse width 312
effectively alters the output voltage waveform.
The switching of the control signals 310 and 320 is controlled by a
processor or a Complex Programmable Logic Device (CPLD) (not
shown). Changes in the duty cycle of the control signals 310 and
320 are used to control the output voltage.
The control signals 310 and 320 typically operate at 8 kHz, which
would be removed by the low pass filters 120 and 140. The control
signals 310 and 320, however, can operate at different switching
frequencies.
In one arrangement, the voltage regulation circuit 100 and the
associated components are limited to a maximum current. In the
event that the current exceeds the maximum current, then the
voltage regulation circuit 100 is shut down and a bypass relay (not
shown) is activated to bypass the voltage regulation circuit 100.
This ensures the voltage regulation transformer circuit 100 is
protected and not over stressed.
As described hereinbefore, and in particular in Table 1, the
switches 160 and 170 must not be closed at the same time.
Therefore, when transitioning from the closing-to-opening of the
switch 170 to the opening-to-closing of the switch 160, the second
control signal 320 goes to the low level (i.e., opening the switch
170) in advance of the first control signal 310 going high (i.e.,
closing the switch 160). A pre-determined period 322, where both
control signals 310 and 320 are held at the low position, is
maintained between the second control signal 320 going low and the
first control signal 310 going high to ensure that both switches
160 and 170 never close at the same time. Further, the transition
period of when both of the control signals 310 and 320 are low
provide a relaxation time to allow the switching transients to
decay.
Similarly, when transitioning between the closing-to-opening of the
switch 160 to the opening-to-closing of the switch 170, the first
control signal 310 goes to the low level (i.e., opening the switch
160) in advance of the second control signal 320 going high (i.e.,
closing the switch 170). A pre-determined period 324, where both
control signals 310 and 320 are held at the low position, is
maintained between the first control signal 310 going low and the
second control signal 320 going high to ensure that both switches
160 and 170 never close at the same time.
As described hereinbefore, the output voltage 150 is the average of
the output voltage waveform at the second end 132B as determined by
the output filter 140 and the duration of the respective voltages
210 and 220 as determined by the control signals 310 and 320.
INDUSTRIAL APPLICABILITY
The arrangements described are applicable to voltage
regulation.
The foregoing describes only some embodiments of the present
invention, and modifications and/or changes can be made thereto
without departing from the scope and spirit of the invention, the
embodiments being illustrative and not restrictive.
In the context of this specification, the word "comprising" means
"including principally but not necessarily solely" or "having" or
"including", and not "consisting only of". Variations of the word
"comprising", such as "comprise" and "comprises" have
correspondingly varied meanings.
* * * * *